1. Field of the Invention
The present invention relates, generally, to communication systems and processes which use radio frequency (RF) transmitters and receivers (transceivers), and, in particular embodiments, to systems and processes for communication transceivers employing replaceable modules to minimize size, weight, complexity, power consumption, and cost.
2. Description of Related Art
It has become increasingly important to minimize the size, weight, complexity, power consumption, and cost of various electronic devices, especially personal communication devices such as cellular telephones, personal pagers, cordless telephones, and the like. One way to minimize such characteristics is to minimize the number of components and functions required in the electronic device, or to perform multiple functions using the same components. However, personal communication devices such as cellular telephones often utilize complex circuitry with a number of power-inefficient components for performing multiple functions. This is especially true in modern cellular communications, where several different communication standards are employed worldwide, and cellular telephones with the flexibility to operate under multiple communications standards are highly desirable from a consumer and manufacturing perspective.
For example, the Global System for Mobile (GSM) communication standard is a world-wide mode of digital cellular communication operating over three different frequency bands. GSM-900 operates in the 900 MHz frequency band and is currently used in Europe and Asia. DCS is another digital cellular standard based on GSM technology, operating in the 1800 MHz frequency band and also currently used in Europe and Asia. The United States uses PCS, a third digital cellular standard similar to DCS, but operating in the 1900 MHz band. GSM is currently used in approximately 154 countries, including the geographic areas of North Africa, India, China, Europe, the Middle East, and Taiwan.
However, GSM is not the only mode of cellular communication. CDMA is another mode of digital cellular communication operating in either the 900 or 1900 MHz band. CDMA is one of the most widely used modes of cellular communication in the United States, and is the most widely used mode of cellular communication in Korea. CDMA is also being used in China, India, and Taiwan. It should be noted that other communication standards also exist around the world.
With improved voice and data communications and political climates continuing to expand the world market, a xe2x80x9cworld telephonexe2x80x9d capable of operating in many different countries is of interest to international business and recreational travelers. Multi-mode, multi-band cellular telephones with shared functionality and an optimized architecture capable of operating under all of these standards afford consumers widespread applicability and allow manufacturers to benefit from the cost-efficiency of a common design.
However, multi-mode, multi-band cellular telephones present a number of design challenges. Conventional single-band transmitters typically require two separate frequencies, a fixed intermediate frequency (IF) for modulation and a tunable RF for upconversion. Conventional single-band receivers also typically require two separate frequencies, a tunable RF for downconversion and a fixed IF for demodulation. Thus, a single-band cellular telephone may require as many as four different frequency sources. Multi-band and multi-mode cellular telephones exacerbate the problem because the modulation, upconversion, downconversion, and demodulation processes for each band and mode may operate at different frequencies and amplitudes. Furthermore, the frequencies and amplitudes employed by each band and mode may require different filters and amplifiers for the transmit and receive function of each band. The design challenge of producing cellular telephones of minimal size, weight, complexity, power consumption, and cost is thus compounded by multi-mode, multi-band cellular telephones.
A current trend in attempting to solve this design challenge is the concept of a xe2x80x9csoftware radio,xe2x80x9d which focuses on utilizing as much digital processing as possible. By utilizing digital technology, multi-mode, multi-band transceiver functions can be implemented more generically, with fewer analog components and fewer bulky filters. A problem with digital technology, however, is that a higher resolution ADC (Analog to Digital Converter) may be required. The digital components may be more inefficient than functionally comparable analog components, resulting in greater power consumption. Greater power consumption, in turn, may require a larger battery, negating any size and weight saving achieved by the use of digital technology.
Therefore, it is an advantage of embodiments of the present invention to provide a system and process for supporting multiple wireless standards with a single circuit architecture to minimize size, weight, complexity, power consumption, and cost.
It is a further advantage of embodiments of the present invention to provide a system and process for supporting multiple wireless standards with a single circuit architecture capable of receiving a replaceable module optimized for one or more communication standards to minimize size and power consumption.
These and other objects are accomplished according to a communication system for the wireless transmission of information through a single antenna. The communication system comprises a handset and one or more modules capable of being coupled to the handset. The handset processes baseband information signals being received and transmitted, and transmits and receives RF information signals through its antenna. Each module is removably couplable to the handset for converting baseband information signals into RF information signals for transmission, and for converting received RF information signals into baseband information signals. Each removably couplable module is optimized to enable wireless communication in accordance with at least one communication standard when coupled to the handset. By coupling the appropriate module with the handset, wireless communication in a number of geographic locations may be achieved.